Alleviation of Cu toxicity in Oenothera picensis by copper-adapted arbuscular mycorrhizal fungi and treated agrowaste residue

The alleviation of copper (Cu) toxicity in the pseudometallophyte Oenothera picensis via arbuscular mycorrhizal fungi (AMF) inoculation and/or sugar beet agrowaste (SB) application was evaluated at increasing soil Cu levels. Plants were grown in Cu-treated soils (0, 100 or 500 mg Cu kg(-1)), either with or without SB application, and inoculated with: (i) Cu-adapted Glomeromycotan fungi (GA); (ii) Glomus claroideum (GC); or (iii) no fungus (uninoculated). Application of SB amendment increased shoot biomass 2-8-fold with respect to the unamended soils, and allowed the survival of non-mycorrhizal- and GC-inoculated plants, even at the highest Cu level. Additionally, SB application increased shoot Cu content at higher Cu levels and shoot P content especially at lower Cu levels. In general, compared to GC-inoculated plants, GA inoculation caused a decrease in both superoxide dismutase and ascorbate peroxidase antioxidant enzyme activities in shoots (up to levels of 100 mg Cu kg(-1)), as well as glutathione reductase and catalase activities (up to 500 mg Cu kg(-1)). Finally, in SB treated plants, GA colonization was higher as compared to GC-inoculated plants, especially at the highest Cu level. These results suggest a relevant role of Glomeromycotan fungal populations isolated from Cu-polluted environments in the alleviation of Cu toxicity that could allow their use in remediation programs for Cu-polluted soils. (C) 2011 Elsevier B.V. All rights reserved.